-I can't tell you which is best and not all software is approved on all option exchanges, but check out: Actant, Option City and ORC.

-with collocation they can run from $3500 to $8,000 plus the cost of membership and the related costs to being a broker dealer. That can run from $5000 up to $15,000.

-they all have commitments from 90 days to a year.

-I used Actant on the Amex. I liked it. Actant and Option city can both be used as a pro-customer, non member also. You can't do bulk market changes way a member can and have to cancel/replace. Instead of leaving markets out there, the software enters bid and offers when your skew see value. You also get picked off less this way and the cost is much less because your not required to be a member or be a broker dealer.